Large displays (e.g., billboards), such as those commonly used for advertising in cities and along roads, are widely used to display images, video, or text. The graphics may be projected on a single panel or extended across multiple panels. Each panel may have an array of light emitting diodes (LEDs) to generate the visual graphics. The LED panels may be conventional panels made using discrete LEDs or surface-mounted device (SMD) panels. Most outdoor screens and some indoor screens are built around discrete LEDs, which are also known as individually mounted LEDs. A cluster of red, green, and blue diodes, or alternatively, a tri-color diode, is driven together to form a full-color pixel, usually square in shape. These pixels are spaced evenly apart and are measured from center to center for absolute pixel resolution.
These panels may be powered by one or more external power supplies and a single power supply can power a single panel or a group of panels. Generally, external power supplies are bulky and require separate maintenance and assembly. Additionally, as several panels may be powered by an external power supply, in the case of failure, multiple display panels may simultaneously lose power.
In some instances, manufacturers mount individual encased power supplies inside the display panel housing. This typically results in an increase in the thickness and weight of the individual panels and the bulk of the whole assembly.